1. Field of the Invention
The present invention relates to a pressure transducer assembly for measuring the pressure in a process circuit of a process plant.
2. Description of Related Art
In process plants, such as chemical and refining plants, pressure transducers installed on the site are used as field instruments to measure fluid pressure. Pressure transducers are used for example to measure the fluid pressure and to detect the extent that the process circuit is full of fluid. Measuring diaphragms with differential pressure transducers are frequently used to ascertain the fluid flow in the circuit.
A known pressure transducer assembly of this type for use on a process circuit of a process plant is disclosed in German patent DE 199 21 172 C1. The pressure transducer assembly comprises a pressure transducer carried on a valve block. A fluid line is disposed between a process circuit and the valve block. A flow control unit in the form of a stop valve is installed between the process circuit and the valve block. A first flange connection is provided between the connection on the process circuit and fluid line. A second flange connection is provided between the valve block of the pressure transducer and the fluid line. The fluid line runs through the stop valve upstream of the valve block. The stop valve is connected to the process circuit at an input side downstream of the process circuit flange connection which operates as a first portion of the fluid line. The stop valve has a chamber in which a movable valve member is received. It can be moved from a flow-through position, in which a flow-through connection is established from the input side of the stop valve before to the valve block of the pressure transducer following the valve member of the stop valve, and into a closing position in which the flow-through connection is closed. Along the fluid line in the pressure transducer, a pressure cell with a pressure sensor is installed, whereby the pressure sensor is connected to an electronic measuring system for indicating the pressure of the process circuit when fluid is directed through the stop valve and into the valve block.
In order to reduce the cost of the installation, this typical pressure transducer assembly is connected directly into the process circuit whereby the short and stable interconnected components of the pressure transducer assembly take on a support function. The stop valve, which may be, for example, in the form of a ball valve or tap cock, is connected to numerous valve blocks on the downstream side to which transducer bodies, and with them the measuring cells contained therein and the housing of the electronic measuring systems are in turn connected. In a differential pressure transducer assembly of this type, and also known from DE 199 21 172 C1, two parallel fluid pressure measuring circuits, each with an associated stop valve and each with a downstream valve block to a differential pressure transducer are installed.
This known and expensive connection of one stop valve for each valve block, linked one after the other in a sequential manner in a circuit is necessary to make it possible to carry out manipulations on a given pressure transducer, such as for maintenance or transducer replacement, as well as to manage the pressure conditions downstream of a locked stop valve, as well as media-caused problems such as in the presence of toxic media. In addition, selected stop valves can be opened in dead spaces in order to achieve targeted pressure reduction in a known manner after the closing of an upstream stop valve when process pressure still prevails. However, these dead spaces downstream of the closed stop valve may also cause problems, for example, with respect to a temperature expansion or sterility of media residues remaining therein, so that such dead spaces may possibly prove costly to rinse out and must be sterilized e.g. for food production.
Accordingly, it is an object of the present invention to further develop a pressure transducer assembly of this type in such manner that the installation becomes more economical and compact and so that the above-mentioned disadvantages may not occur or at least be reduced to a great extent.